A wide variety of structures for disposable absorbent articles to collect body fluids are known in the art. Commercial absorbent articles include diapers, adult incontinence products, catamenials and bandages. Disposable products of this type comprise some functional members for receiving, absorbing and retaining fluids. Generally, such absorbent articles contain a core of absorbent materials mainly comprising fibrous cellulose. Typically, such articles include a fluid-permeable topsheet, an absorbent core and a fluid-impermeable backsheet.
In the case of catamenial pads, women have come to expect a high level of performance in terms of comfort and fit, retention of fluid, and minimal staining. Above all, leakage of fluid from the pad onto undergarments is regarded as totally unacceptable.
Improving the performance of sanitary napkins continues to be a formidable undertaking, although a number of improvements have been made in both their materials and structures. However, eliminating leakage, particularly along the inside of the thighs, without compromising fit and comfort, has not met the desired needs of the consumer.
Leakage from sanitary napkins is generally attributed to a high concentration of fluid at the point where the menses exits the body and immediately contacts the surface of the napkin. At this point of deposit, the napkin's absorbent material quickly becomes supersaturated. The blood migrates radially from this point and leaks from the sides nearest the wearer's legs. This often results in the smearing of blood on the body and soiling of the undergarments. Attempts to eliminate leakage include: construction of a densified edge to hold the fluid back (U.S. Pat. No. 4,820,295, Chapas et al, issued Apr. 11, 1989); barrier sheets surrounding the article (U.S. Pat. No. 4,666,439, Williams et al, issued May 19, 1987); and "winged" side edges which wrap around the panties (U.S. Pat. No. 4,701,177, Ellis et al, issued Oct. 10, 1987, incorporated herein by reference).
Unfortunately, over-densifying sections of the sanitary napkins detracts from comfort, in-use. Some users are not attracted to the "winged" product, and others are not satisfied with the barrier product. However, since a large part of most absorbent articles remains relatively dry and not utilized, it has now been determined that providing a means to direct fluid from the point of deposit to the areas of the article not fully utilized will avoid supersaturation and considerably reduce or eliminate leakage.
Apart from undergarment soiling, the user of modern sanitary napkins, and the like, has come to expect that the surface of such articles will provide a cleaner, more sanitary and drier aspect than common cloth or nonwoven materials have historically provided. Thus, modern sanitary napkins, diapers and incontinence devices are typically provided with topsheets that are designed to move fluids rapidly through said topsheets and into an underlying absorbent core for storage. As can be envisaged, the more rapid and thorough this movement, the drier and cleaner the surface of the article.
Stated succinctly, the present invention not only provides the desired, directional movement of fluids noted above, which allows improved use of the overall absorbent capacity of the article and less side-leakage, but also provides means to draw fluids through the topsheet, thereby enhancing the desired dry, sanitary benefits, in-use.
Furthermore, the articles which employ the technology embodied in the present invention are more comfortable and better fitting than articles which rely, for example, on highly dense absorbent core regions to achieve fluid movement. Stated otherwise, the technology herein achieves the fluid directionality and handling characteristics available from dense, but uncomfortable, cores in a soft, pliable, low-density and comfortable pad.